Thank you for asking for feedback before posting to a mainlist! Great work, too, because I think this needs some major polishing, but I do think the core kernel can be successful. It's not incredibly unique, but I think if you changed the recovery hook, maybe hinting in some document that this was a failed creation by a communist sympathizer during the 1960s to spread communism, this could be pretty good.

First off, it definitely looks like you are struggling with the clinical tone. You definitely remain clinical, and kudos for that, but it gets confusing and wordy in some aspects. You're using the active voice well, in my opinion, so keep it up.

All instances of SCP-xxxx are to be locked in standard Safe class storage container. It is to be placedkept in an opaque plastic case at all times, except for testing conditions. Any instances of SCP-xxxx-1 and 2 are to be terminated immediately unless in testing conditions. A containment breach of SCP-xxxx is to be handled by security staff with full auditory protection, and instances of SCP-xxxx-1 and 2 are not to be approached by any personnel without stated protection.

It is a 50 page pamphlet, and.sScans of its material have not shown any anomalies, meaning the anomalous effect is contained in the text written in SCP-xxxx-1.

Also unnecessary information for your target audience.

Its language changes to match the mothernative tongue of the observer. The schools of thought also vary, changing between Marxist, Stalinist, Leninist, and Maoist.

"Native Tongue" is more clinical that "mother tongue."

There is correlation between the school the observer sees and what they most identify with.

It's an odd sentence. You could delete it altogether. You could also say something like "The version seen appears to correlate with the subjects' existing disposition."

SCP-xxxx will display its memetic properties when viewed by an individual while no instances of SCP-xxxx-1 exist.

You can add that to the end of the document or cut it altogether. It's just confusing, here.

The subject will be compelled to read SCP-XXXX in its entiretythe book, but will not put themselves in danger to do so. Upon reading the books contentsSCP-XXXX, the subject will henceforth become an instance of SCP-xxxx-1. As it reads, SCP-xxxx-1 will become more and more obsessed with SCP-xxxx. Eventually, SCP-xxxx-1 will stop reading SCP-xxxx and begin hunting for followerssentient organisms. Upon finding a living thing fulfilling the criteriaanother person, SCP-xxxx-1 will begin to read from SCP-xxxx. The organism second individual, now known as SCP-xxxx-2, will become enthralled by SCP-xxxx-1.

I haven't said it yet, but I would make it so that this only works on people. Having it work on animals is confusing to write, confusing to read, and unnecessary. I've made some other stylistic changes that I think keep the flow.

Testing has shown that all creatures showing some form of intelligence and social structures are susceptible to this effect. Instances of SCP-xxxx-2 show extreme devotion to SCP-xxxx-1, and will takepercieve all messages from them as inspiring speeches. Once a number of instances of SCP-xxxx-2 have been created (results vary between 20-50 instances, depending on said schools of thought), SCP-xxxx-1 will attempt to organise its followers in a way adhering to communism. Fully functioning communist communities have been set up during test conditions. Over time, correlating to the number of SCP-xxxx-2, SCP-xxxx-1 will begin adjusting its “society” to fit its own specific branch of ideas. This also changes dependentdependant on the individual and original school displayed by SCP-xxxx.

And these.

D-3491: Maoism: The society became focused on the worship of Mao himself, with SCP-xxxx-1 taking a role of religious leader. Instances of SCP-xxxx-2 would congregate and listen to SCPSPC-xxxx-1 read from SCP-xxxx.

D-4532: Leninism: SCP-xxxx-1 began to create an "armed guard", and attempted continuously to convince foundation personnel to overthrow the "bourgeoisie" head researchers.

D-7834: Maoism: SCP-xxxx-1 began to force SCP-xxxx-2 to work much harder than before, in order to fulfill increasingly unstable plans for the future. Interestingly, SCP-xxxx-2 also began to change, with instances lying to SCP-xxxx-1 about the yields of their work, for "rewards" from SCP-xxxx-1

And these.

D-6892:Stalinism: [DATA EXPUNGED]

I recommend you either write it out, or get rid of it. People generally don't like entire experiments expunged. It -might- work in this case, it's your call.

Researcher’s note: As of incident xxxx-a, all instances of SCP-xxxx-1 who follow the school of Marxism are to be terminated before telepathic abilities develop to prevent another incident of this type. -Researcher Trotsky.

I would just say that testing has been suspended.

SCP-xxxx was recovered from the town of █████ , Alabama. The town had sent a letter to the US government, declaring itself a “Commune” and independent from the United States. The national guard were sent in, but upon no reply being received, the Foundation was contacted by the US government. Personnel in full combat equipment, which included auditory protection, and unaware of the properties of SCP-xxxx, shot and killed the SCP-xxxx-1 instance, resulting in ████ casualties, which was covered up under the pretence of a epidemic, with the town quarantined off until the incident is out of the public eye to avoid discovery of the Foundations involvement.

You've got some long, long sentences in there.

Addendum 1: Animals are just as capable of being affected by SCP-xxxx-1, but cannot become an instance of SCP-xxxx-1, and are not affected by SCP-xxxx.

I really suggest you axe that bit.

Addendum 2: An instance of SCP-xxxx-2 seems to be “curable” by:
A: Moving over 50km from the SCP-xxxx-1 instance.
B: SCP-xxxx being damaged (Page bent or torn). This will cause all instances of SCP-xxxx-2 to “wake up” retaining no memories of events since being converted to an instance. SCP-xxxx-1 will be terminated in a similar fashion to SCP-xxxx-2 instances in the result of SCP-xxxx-1’s death.

I'd say get rid of B. So it can never be used again? It's not really necessary, in any case, you've already said all the interesting stuff. For that matter, just get rid of all of it. It doesn't matter that much. It's Red or Dead!

Researchers note: Due to the effective system put in place by SCP-xxxx, I suggest a project involving using multiple D-class to create efficient labour camps with SCP-xxxx-1, swapping out the Instance of SCP-xxxx-1 to avoid any of the undesirable secondary characteristics developing and impeding production. – Head Researcher Dhe.

No, that's not professional at all. Using SCPs for productive purposes? We don't do that. Just get rid of that bit.

Anyways, I like it, and I think it could be successful on the mainlist, so clean it up!

This idea is quite interesting and unique. Abbetik basically said everything I would have, so I don't have a lot of suggestions. The only thing I would say is maybe elaborate and clarify some things about SCP-XXXX-1 and -2. Also, can there be multiple instances of -2? If not, then this isn't a very powerful thing. Maybe have SCP-XXXX-2 go out and attempt to "recruit" other people into listening to SCP-XXXX-1? That might lead to some interesting incident reports about how communist extremists went rampaging through towns to try to make people listen to SCP-XXXX-1.